1. Field of the Invention
The present invention relates to an image processing apparatus and an image processing method capable of suitably executing positioning between volume data acquired by the same modality or different modalities.
2. Description of the Related Art
In recent years, an image processing apparatus for use in a medical image field is used in combination with a medical imaging apparatus such as an ultrasonic diagnosis apparatus, an X-ray CT scanner or a magnetic resonant imaging apparatus, and the image processing apparatus is broadly utilized in many hospitals, inspection institutions and the like. In this image processing apparatus, improvement of an image processing speed or resolution advances, and various images can be presented which are useful as clinical information. The apparatus is utilized in forming a gastrointestinal tract image during checking of causes for blood vessel running, gastrointestinal tumor, formation of plaques (spots), stenochoria or the like in, for example, simulation or the like before an operation.
In image diagnosis in which such image processing apparatus is utilized, there is a case where there are compared, with one another, image groups (constituted of a plurality of two-dimensional image data, referred to also as volume data) collected in different timings (times) or different modalities, and a progress of an affected part with an elapse of time is observed. In this case, the image groups need to be corresponded (e.g., positioned) with each other. Heretofore, there has been, for example, an image processing apparatus in which a local subtraction image is generated by subtraction of an image of a diagnosis region as a part of one specific image (digital image) and a local image of the corresponding region as a part of another image corresponding to this diagnosis region. Accordingly, a person who interprets a radiogram can interpret the radiogram, while confirming a change of the diagnosis region with an elapse of time or a difference between a region state and a normal state (see, e.g., Jpn. Pat. Appln. KOKAI Publication No. 7-37074). There is also an image processing apparatus in which a first image set and a second image set having different photographing times are subjected to MPR processing, respectively, and images are positioned using MPR images (see, e.g., Jpn. Pat. Appln. KOKAI Publication No. 2004-96417).
However, in the conventional image processing apparatus, in principle, each image needs to be positioned. Therefore, when the image groups including a plurality of image data, especially volume data, are corresponded with each other in a conventional technology, in principle, all images constituting the volume data need to be confirmed and positioned, and large operation burdens are imposed on an operator.
Moreover, in a case where image sets including a plurality of images are corresponded with each other by use of the MPR images, the MPR image indicates an arbitrary cut. Therefore, in a case where a characteristic portion which does not exist in the cut exists externally from an MPR object region, precision cannot be said to be sufficient in some case.